In medical imaging examinations, by way of ionizing rays, in particular with x-rays, monitoring and evaluation of the radiation dose taken up by the patient is usual and in some cases is a legislative requirement. A medical imaging examination by way of ionizing radiation can involve an x-ray recording or a computed tomography imaging for example.
Since information processing systems for image data from medical examinations, although they can read image data, cannot however always read it with metadata of any given formats, an expanded process is needed for storing metadata about an examination as rasterized text in a dose report image, and for making the dose report image available. Metadata can in particular involve personal data of the examined patient (for example name, age, date of birth, address and/or sex) as well as dose data of the examination, for example a CTDI (Computed Tomography Dose Index), the WED (Water-Equivalent Diameter) or the DLP (Dose Length Product). The name dose information image is also known as a synonym for dose report image.
For efficient monitoring and evaluation of the dose data it is desirable to store these dose report images centrally, in particular also with a third-party provider for storage services (a so-called cloud storage provider). However for this the personal data must be removed from the dose report image or said data must be anonymized, in order to satisfy legislative requirements for data protection.
For this it is known that individual personal data can be localized via optical character recognition (abbreviated to OCR) and anonymized on the basis of its position. However, because of the variability of the personal data characters, recognition is difficult, for example a name of a person can be not in widespread use or can contain characters from other character sets (umlauts, accents, Arabic or Chinese fonts). Furthermore, with such a method it cannot be excluded that personal data continues to be present in the anonymized dose report image.
Furthermore the processing of dose report images based on a positive list is known from the German patent with the file reference DE 10 2015 225 735.5. Here dose report images are transmitted if the information contained therein can be extracted via text recognition, and the corresponding medical imaging device is transmitted to a positive list. It is not disclosed here however how personal data can be anonymized in the dose report images.